docs: def minute(self, symbol=None):
          '''
          获取1分钟线
  
          :param symbol:
          :return: pd.dataFrame or None
          '''
          symbol = self.find_path(symbol, subdir='minline', ext=['lc1', '1'])
          reader = TdxLCMinBarReader()
  
          if symbol is not None:
              return reader.get_df(symbol)
  
          return None